<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Document</title>
  </head>
  <body>
    <script>
      class Father {
        say() {
          return '我是父类';
        }
      }
      class Son extends Father {
        say() {
          console.log(super.say() + '的子类');
        }
      }
      var son = new Son(1, 2);
      son.say();			// 输出结果：我是父类的子类
    </script>
  </body>
</html>